Battery life is an important aspect of marketing mobile communication devices. Battery life is often expressed in terms of “talk time” or “stand by time.” It is desirable to provide longer operating times between recharge cycles, or before changing the battery of the mobile communication device. Consequently, manufacturers are constantly trying to reduce the power consumption rates of mobile communication device with each successive design.
The transmitter of a mobile communication device operates at a high power level when transmitting, but a significant power level is required when receiving as well. Reducing the amount of time the receiver needs to be on will therefore reduce the power consumption of the mobile communication device. Accordingly, it is typical that the transmitter and receiver be put into a low power state until needed.
Typically in mobile communication systems when the mobile communication device is not involved in a call it still must periodically monitor for incoming calls or other signals. In time divisioned, multiple access systems, the mobile communication device is typically assigned to a paging channel, and periodically must power up the receiver to receive a transmission from the communication system. Typically the paging transmission includes a slot descriptor block which indicates the nature of the information in the payload of the paging frame. The slot descriptor block also includes expected symbols, such as pilot symbols, which may be used for channel estimation.
Even if the slot descriptor block indicates the payload of the present frame has no data, the receiver is not shut off at the end of the slot descriptor block because, in addition to receiving the information regarding payload in the slot descriptor block, there are additional expected symbols beyond the slot descriptor block the mobile communication device receives to perform channel estimation in less than optimal signal conditions. These additional symbols embedded in the payload section must be received, especially in poor channel conditions, to maintain good channel estimation, even when there is no useful information in the payload for the mobile communication device. But under good signal conditions, it may not be necessary to receive more symbols than those in the slot descriptor block. Therefore there is a need for a way to shut off the receiver prior to the end of the receive time slot without losing performance.